High Availability Theoretical Basics - Schneider Electric

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Calculation Example High Availability Theoretical Basics In this example, we calculate the availability of a PAC Station using shared distributed I/O Islands. The following illustration shows the final configuration: This calculation applies the equations given by basic probability analysis. To do this calculation, a spreadsheet was developed. These are the figures applied in the spreadsheet: Failure rate: λ = 1/MTBF Reliability: R(t) = e -λt n Total serial Systems Failure Rate λ = ∑ λ S i i = 1 Total MTBF serial Systems = 1 / λs Availability = MTBF/ MTBF+ MTTR Unavailability = 1 – Availability Unavailability over years: Unavailability × hours (one year = 8460 hours) The following table shows the method to perform the calculation: Step Action 1 Perform the calculation of the Standalone CPU. 2 Perform the calculation of a distributed island. 3 Based on the serial structure, add up the results from Steps 1 and 2. Note: A common variant of in-rack I/O Module stations are I/O Islands, distributed on an Ethernet communication network. Schneider Electric offers a versatile family named Advantys STB, which can be used to define such architectures. Step 1: Calculation linked to the Standalone CPU Rack. The following figures represent the Standalone CPU Rack: 22
High Availability Theoretical Basics The following screenshot is the spreadsheet corresponding to this analysis. Step 2: Calculation linked to the STB Island. The following figures represent the Distributed I/O on STB Island: The following screenshot is the spreadsheet corresponding to this analysis: 23
Page 1: System Technical Note How can I...
Page 4 and 5: Introduction to High Availability 4
Page 6 and 7: Introduction to High Availability A
Page 8 and 9: Guide Scope High Availability Theor
Page 10 and 11: Bathtub Curve High Availability The
Page 12 and 13: • MTTF (or MTTFF): Mean Time to F
Page 14 and 15: Availability Definition Mathematics
Page 16 and 17: Classification Reliability Definiti
Page 18 and 19: High Availability Theoretical Basic
Page 20 and 21: Serial RBD Reliability High Availab
Page 24 and 25: High Availability Theoretical Basic
Page 26 and 27: Redundant System Reliability, over
Page 28 and 29: Step 1: Calculation linked to the S
Page 30 and 31: Conclusion Serial System High Avail
Page 32 and 33: Information Management Level Redund
Page 34 and 35: High Availability with Collaborativ
Page 36 and 37: . Clients: Operator Workstations Hi
Page 38 and 39: Target: I/O Device High Availabilit
Page 42 and 43: Plant Topology High Availability wi
Page 44 and 45: Ring Topology High Availability wit
Page 52 and 53: Fast HIPER-Ring High Availability w
Page 54 and 55: Control System Level Redundancy Pri
Page 56 and 57: In-Rack and Remote I/O Architecture
Page 62 and 63: Distributed I/O Architectures Ether
Page 64 and 65: Profibus Architecture High Availabi
Page 66 and 67: Redundancy and Safety High Availabi
Page 68 and 69: Controlled Switchover High Availabi
Page 70 and 71: Switchover Latencies High Availabil
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Conclusion Quantum Hot Standby Esse
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Benefits Standard Offer Conclusion
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Appendix Glossary Appendix Note: th
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15) Hidden Failure FTA illustration
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26) Non-Detectable Failure Appendix
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Standards General purpose Appendix
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Calculation Examples The calculatio
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Redundant Architecture Calculation
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Redundant PLC System, Using Shared
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Calculation Examples For this Seria
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Consider a common misuse of reliabi
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Schneider Electric Industries SAS H
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High Availability Theoretical Basics - Schneider Electric

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